function setOpAndProd()
{
	 prodSelect = document.getElementById("prodSelect");

	 selectorProduct = document.getElementById("selectorProduct");
	 selectorOperator = document.getElementById("selectorOperator");

	 if (selectorProduct.value == 0 || selectorProduct.value == 2 || selectorProduct.value == 3 || selectorProduct.value == 7)
    {
			selectorOperator.disabled = false;
    }
    else
    {
			selectorOperator.value = 0;
			selectorOperator.disabled = true;
    }
}